Muzzleloader ignition types
Muzzleloader seasons were originally envisioned as opportunities to hunt with primitive muzzleloading firearms, and some states like Colorado and Oregon still prohibit muzzleloading rifles with inline ignition systems.
Traditional sidelock muzzleloaders ignite the powder charge with a spark from a flint or with a percussion cap contained by a lock that is attached offset to the barrel. These are used with traditional blackpowder.
Inline muzzleloaders, in which the percussion cap is attached to a breech plug, direct the ignition charge directly into the powder charge. They are designed for modern blackpowder substitutes like Pyrodex, Triple Seven and Blackhorn 209.
More recent adaptations use 209 shotgun primers which ignite newer powders more consistently. Some even use large rifle primers, which throws a much hotter, higher pressure charge than percussion caps or shotgun primers.
Inline muzzleloaders are more dependable than sidelocks, but they still must be loaded from the muzzle, and every step of the loading and firing process must be done correctly for the rifle to fire.
If a bullet is not firmly seated atop the powder charge, for example, powder can be too loose, or it can settle forward in the barrel and prevent or delay discharge. Excessive lubricant or residual cleaning solvent in the barrel can prevent powder from properly igniting, as well.
In 2016, during a controlled muzzleloader hunt at Madison County Wildlife Management Area, I used the most modern setup available, a Thompson/Center Omega fitted with a VariFlame conversion that enabled me to use large rifle primers with Blackhorn 209, the most modern powder on the market.
It worked flawlessly in practice before the season, but it was an epic fail when the biggest buck I’ve seen on public land stepped clear 70 yards away. There was a delay between the ignition of primer and powder, probably because I seated the bullet improperly. I missed.
That element of potential failure makes all muzzleloaders equal.
— Bryan Hendricks